As a method for producing an optically active 2-alkanol, several methods, such as an optical resolution method of an ester exchange reaction using enzyme or an optical resolution method using hydrolysis, are known. Specifically, many methods reported in recent years are those for producing compounds having optical purity of more than 90% ee. However, in almost methods, only one of both enantiomers has good purity, but the other has optical purity of less than 80% ee (for example, Tetrahedron Lett., 1995, 36, 6663; Biotechnol. Lett., 1992, 15, 2159).
Further, there are some methods for producing both enantiomers having optical purity of more than 90% ee (for example, Tetahedron Asymm., 1995, 6, 1217; Tetrahedron Lett., 1993, 34, 1367; Japanese Patent Laid-open Publication No. 6-169794). However, in the stereoselectivity, both enantiomers having optical purity of more than 99% ee are unknown.
In optical active 2-alkanol as liquid crystal materials, both enantiomers are necessary, and each optical purity of 99 % ee or more is required. For this reason, hitherto, it has been conducted to use insufficient methods such as recrystallization after leading the compound obtained by optical resolution to its derivative, or repeated enzyme reaction, to provide compounds having optical purity of more than 99% ee.
There are transesterification reactions using the enzyme derived from Candida antarctica (microbiotics) (Tetrahedron Lett., 36(37), 6663-4), or using aliphatic acid trichloroethyl ester (Japanese Patent Publication No. 06-104661). In general, stereoselectivity of the transesterification reaction using an enzyme is influenced by the combination of alcohol, which is a substrate, ester, which is an acylating agent, and the enzyme, so that the suitability is unknown until the reaction is conducted. In all of the said methods, the optical purity is no more than 90% ee.
Accordingly, a simple method for producing optical active 2-alkanol having both enantiomers showing optical purity of more than 99% ee has been desired.